package bitmanipulation;

/**
 * Created by Tzachi on 16/10/2014.
 * <p>
 * You are given two 32-bit numbers, N and M, and two bit positions, i and j.
 * Write a method to set all bits between i and j in N equal to M (e.g., M becomes a substring of N located at i
 * and starting at j).
 * EXAMPLE:
 * Input: N = 10000000000, M = 10101, i = 2, j = 6
 * Output: N = 10001010100
 */

public class Masking {
    public static int updateBits(int n, int m, int i, int j) {
        int max = ~0; /* All 1’s */

        // 1’s through position j, then 0’s
        int left = max - ((1 << j) - 1);

        // 1’s after position i
        int right = ((1 << i) - 1);

        // 1’s, with 0s between i and j
        int mask = left | right;

        // Clear i through j, then put m in there
        return (n & mask) | (m << i);
    }
}
